1. Technical Field
This invention relates to ultrasonic surgical systems and, more particularly, to an improved apparatus for facilitating the performance of surgical procedures such as simultaneous soft tissue dissection and cauterization of large and small blood vessels through the use of a precisely controlled ultrasonically vibrating instrument, such as a blade or scalpel.
2. Background
It is known that electric scalpels and lasers can be used as surgical instruments to perform the dual function of simultaneously effecting the incision and hemostatis of soft tissue by cauterizing tissues and blood vessels. However, such instruments employ very high temperatures to achieve coagulation, causing vaporization and fumes as well as splattering. Additionally, the use of such instruments often results in relatively wide zones of thermal tissue damage.
Cutting and cauterizing of tissue by means of surgical blades vibrated at high speeds by ultrasonic drive mechanisms is also well known. In such systems, an ultrasonic generator is provided which produces an electrical signal of a particular voltage, current and frequency, e.g., 55,500 cycles per second. The generator is connected by a cable to a handpiece, which contains piezoceramic elements forming an ultrasonic transducer. In response to a switch on the handpiece or a foot switch connected to the generator by another cable, the generator signal is applied to the transducer, which causes a longitudinal vibration of its elements. A structure connects the transducer to a surgical blade, which is thus vibrated at ultrasonic frequencies when the generator signal is applied to the transducer. The structure is designed to resonate at the selected frequency, thus amplifying the motion initiated by the transducer.
The blade is often non-symmetrical in shape and, during the surgical procedure, the physician manipulates the handpiece to cause the blade to contact the tissue to be treated. Because the switch which controls operation of the blade is disposed on the handpiece, the location of the switch may at times prevent the physician from contacting tissue with the desired orientation of the blade because the relative position between the switch and the blade may prevent or render it difficult for the physician to manipulate the blade to the proper position while still being able to activate the switch with his/her fingers.
Thus, there is a need for a handpiece and switch assembly which will permit the physician to freely access tissue and operate thereon without having to worry about the relative position between the switch and the blade.
Various circuit designs for use in surgical handpiece systems are disclosed herein. The surgical handpiece system includes a switch end cap which is rotatably and preferably detachably connected to the handpiece body with a switch mechanism being provided in the switch end cap. The handpiece body and the switch mechanism are electrically connected to one another in such a manner that permits the switch end cap to be freely rotated about the handpiece body, thereby reducing the number of conductive members needed to communicate the status of each switch.
In one aspect, a sensing circuit is provided within a component of a console which is connected to the handpiece body and provides power thereto. For example, the sensing circuit is designed to detect the presence and direction of conductivity across the conductive members of the handpiece. The switch end cap has a circuit which also permits a reduced number of conductive members to be used to convey signals for monitoring the status of a predetermined number of independent switches, which form a part of the switch end cap. The circuits and the configuration of the conductive members of the handpiece permit the status of two independent switches to be monitored with just two sets of conductive members, rather than the three or more sets of conductive members that would be otherwise required in a more traditional form of circuit monitoring. This reduction in conductive members permits the handpiece construction to be made smaller and more reliable.
In another aspect, the sensing circuit of the handpiece assembly and the circuit of the switch end cap provide a means for detecting and measuring the degree of influence of debris which is located between the conductive members of the handpiece. In addition, the maleffects of such debris is resisted by providing a handpiece using the circuit construction of the present invention.
In yet another aspect, the circuit of the switch end cap in combination with the sensing circuit may be used as a means for identifying the type of switch end cap which is attached to the handpiece body. By varying the circuit used in the switch end cap, the type of switch end cap may be detected by the sensing circuit. Thus, the console, including the sensing circuit, is able to detect what type of switch end cap is attached to the handpiece.
Other features and advantages of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.